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Atoms — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsAtoms1 Mark
Question
For question two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is NOT the correct explanation of A.
  3. A is true, but R is false.
  4. A is false and R is also false.
Assertion (A): Electrons in the atom are held due to coulomb forces.
Reason (R): The atom is stable only because the centripetal force due to Coulomb's law is balanced by the centrifugal force.
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Answer

  1. A is true, but R is false.

Explanation:
According to postulates of Bohr's atom model, the electron revolve around the nucleus in fixed orbit of definite radii. As long as the electron is In a certain orbits it does not radiate any energy. Not only the centripetal force has to be the centrifugal force, even the stable orbits are fixed by Bohr's theory.

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